Rhomboid-shaped wings are known in the art (see Ref (1-4)). The rhomboid wing gets its name from the diamond shape formed by the wings on both sides of an aircraft fuselage. These are excellent examples of designs with unique aero-structural features that have the ability to match mission requirements, and provide superior flight performance. These studies show some unique capabilities of the rhomboid wing, specifically superior aeroelastic properties.
Many efforts have been made with good results to support these thoughts, Ref (5-26). Efforts began at Saint Louis University—Parks College with water tunnel studies of a rhomboid wing to acquire flow visualization data for a proposal to AFRL. The Parks data showed interesting results suggesting that a flow reversal might occur at high angles of attack, Ref (27-29). A MS Thesis followed to study the flows more closely. That work, Ref (30), showed no flow reversal, and indicated no stall to a much higher angle of attack than did the prior work. Another MS thesis, Ref (31), evaluated the buffet properties of a more complete model where the rhomboid wing was mated to a stylized fighter type of fuselage. That study showed no stall to 55 degrees, and a much more muted vortex flow than found on the F-15 and F/A-18 fighters. While the thesis was still pending, a paper, Ref (32), was published. Next, the applicant embarked on work with Variable Geometry Rhomboid Wings, Ref (33-34).
In addition to the Rhomboid wing design, the Applicant worked in parallel with the use of torsion bars in straight wings for control of wing twist. This provided a means to alter the loads on the wings, thus controlling maneuvering. The applicant made the surprising discovery that the torsion bar wing-warping technique enhanced the ability to control aeroelasticity to adjust lift to drag ratio, control flutter and gust and buffet response, Ref (35-37). Because of the synergism of the rhomboid wings and wings with torsion bars, the applicant merged those two ideas, and was issued a US patent, Ref (40) (see also Ref (38-39)). The aeroelastic and flutter properties of the rhomboid wing design were extensively studied, Ref (41-43).
The applicant also has extensive experience with windmills and propellers (see Ref (44-48)). The applicant concluded that current wind turbine and aircraft propulsion propeller blade models often have some serious disadvantages. For example, in helicopters and propeller aircraft, the rotors and propellers must rotate at a very high rotational speed in order to produce sufficient lift and thrust. These high rotational speeds result in greater vibrational forces. Wind turbines have similar problems with vibrational forces because of the high wind speeds needed to turn the blades. These high rotational speeds also result in a great amount of noise. A second problem with the current propeller blade models is the fragile nature of the blade designs. Current blades are long and slender and vulnerable to damage from foreign objects (e.g. gunfire).
The applicant made the surprising discovery that the rhomboid wing design could be employed as a propeller blade to fill a long-felt and unmet need in the art of propellers and rotors.